I can understand limiting the ROM to protect the shoulder girdle, but won't you get weaker in the lower part of the benchpress? Or is this why they tell you to put a towel on your chest or arch your back? So that you get into the habit of doing one of those two things, so that you DON'T surpass your new ROM? Can someone please explain this whole concept to me? Thanks in advance ya'll! (Happy Holidays too)
In general you should always use as full a ROM as possible hat causes NO pain.
This is unless you are say traiing a weakness such as lock outs board presses etc.
always use a full ROM like Phill said, using a towel(carpet press)is just a training method and arching your back puts your lats into it more, these aren't done to protect shoulder girdle.
It really depends on your goals. Some people limit the ROM in their bench to turn the movement into a tricep exercise. Others limit ROM for the sole purpose of strengthening the upper half of their bench. Others, yet, do it for shoulder injury/re-injury prevention.
There's no one reason why people limit the ROM in the bench press. Different people do it for different reasons.